重试 JDBC 连接的最佳方法：

Question

我有一个通过 JDBC 访问的远程数据库。 网络在这方面很差，所以当我有时使用应用程序时，我会得到几个与网络相关的SQLException 。 如果连接失败，我决定重试三次（间隔 2 秒）。 我看到有不同的方法可以做到这一点，但我想知道我的做法是否合适。

其次，由于我使用后台服务访问数据库，如果无法建立连接，我是否需要调用service.restart() ？ 或者只是按照我下面的实现单独重试连接就好了：

public class Sample {
    public Sample() {
        DatabaseService databaseService = new DatabaseService();
        databaseService.start();
        databaseService.setOnFailed(event->{
            //do I do retries here? databaseService.restart();
        });
    }

    public static void main(String[] args) {
       new Sample();
    }

    private class Person {
        private String name;


        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public Person(String name) {
            this.name = name;
        }

    }

    private class DatabaseService extends Service<Person> {
        @Override
        protected Task<Person> createTask() {
            return new GetPersonTask();
        }

        private class GetPersonTask extends Task<Person> {
            @Override
            protected Person call() throws Exception {
                Connection db = DatabaseConnection.getInstance().getConnection();
                //retrieve from database
                return new Person("Sample");
            }
        }
    }
}

public class DatabaseConnection {
    private Connection connection;
    private static DatabaseConnection instance;

    private DatabaseConnection() throws SQLException {
        try {
            Class.forName("org.mariadb.jdbc.Driver");
            String url = "jdbc:mariadb://host.com/database";
            String username = "root";
            String password = "";
            int count = 0;
            int maxTries = 3;
            //3 retries in establishing connection
            while (true) {
                if (count == 0) {
                    System.out.println("INFO: Attempting remote connection to host.com");
                }
                try {
                    this.connection = DriverManager.getConnection(
                            url,
                            username,
                            password
                    );
                    break;
                } catch (Exception e) {
                    System.out.println("ERR: Connection not established - Retrying ");
                    Thread.sleep(2000);
                    if (++count == maxTries) throw e;
                }
            }

        } catch (ClassNotFoundException | InterruptedException e) {
            e.printStackTrace();
        }
    }

    public Connection getConnection() {
        return connection;
    }

    public static DatabaseConnection getInstance() throws SQLException {
        if (instance == null) {
            instance = new DatabaseConnection();
        } else if (instance.getConnection().isClosed()) {
            instance = new DatabaseConnection();
        }
        return instance;
    }
}

我已经更改了我的单例类，改为使用与Hikari的池连接：

public class DatabaseConnection {
    private static HikariDataSource ds;

    static {
        ds = new HikariDataSource();
        String url = "jdbc:mariadb://host.com/database";
        String username = "root";
        String password = "";
        ds.addDataSourceProperty("cachePrepStmts", "true");
        ds.addDataSourceProperty("prepStmtCacheSize", "250");
        ds.addDataSourceProperty("prepStmtCacheSqlLimit", "2048");
        ds.setMaximumPoolSize(20);
        ds.setDriverClassName("org.mariadb.jdbc.Driver");
        ds.setJdbcUrl(url);
        ds.addDataSourceProperty("user", username);
        ds.addDataSourceProperty("password", password);
        ds.setAutoCommit(false);
    }

    private DatabaseConnection() {
    }

    public static Connection getConnection() throws SQLException {
        return ds.getConnection();
    }

}